The herpesviruses comprise a large family of double stranded DNA viruses. They are also a source of the most common viral illnesses in man. Eight of the herpes viruses, herpes simplex virus types 1 and 2 (HSV-1 and HSV-2), varicella zoster virus (VZV), human cytomegalovirus (HCMV), epstein-Barr virus (EBV), and human herpes viruses 6, 7, and 8 (HHV-6, HHV-7, and HHV-8), have been shown to infect humans.
HSV-1 and HSV-2 cause herpetic lesions on the lips and genitals, respectively. They also occasionally cause infections of the eye and encephalitis. HCMV causes birth defects in infants and a variety of diseases in immunocompromised patients such as retinitis, pneumonia, and gastrointestinal disease. VZV is the causative agent of chicken pox and shingles. EBV causes infectious mononucleosis. It can also cause lymphomas in immunocompromised patients and has been associated with Burkitt's lymphoma, nasopharyngeal carcinoma, and Hodgkins disease. HHV-6 is the causative agent of roseola and may be associated with multiple sclerosis and chronic fatigue syndrome. HHV-7 disease association is unclear, but it may be involved in some cases of roseola. HHV-8 has been associated with Karposi's sarcoma, body cavity based lymphomas, and multiple myeloma.
Infection by or reactivation of herpesviruses is also associated with several cardiovascular diseases or conditions in the host such as atherosclerosis and restenosis resulting in inflammation of coronary vessel walls. It is thought that in many patients suffering from restenosis following coronary atherectomy, viral infection, particularly by CMV, plays an important role in the proliferation of the disease. Atherosclerosis is believed to be associated with the overall infectious disease burden in the host and particularly by the herpesviruses such as HSV, CMV, and EBV. Infection in the animal population (livestock and companion) by strains of herpesviruses is endemic including cattle (Bovine herspesvirus 1-5, BHV), sheep (Ovine herpesvirus 1 and 2), dog (Canine herpesvirus 1), horse (Equine herpesvirus 1-8, EHV), cat (Feline herpesvirus 1, FHV), swine (pseudorabies virus, PRV), and many species of fowl. In the case of bovine herpesvirus infection, animals may suffer from ocular, respiratory, or digestive disorders. Pseudorabies is an extremely contagious viral pathogen infecting several species such as cattle, horses, dogs, cats, sheep, and goats leading to rapid death. The virus is benign in adult swine, however, it remains contagious and leads to high mortality in pigs under three weeks. Infection of horses by equine herpesvirus may lead to neurological syndromes, respiratory disease, and neonatal disease. Herpesvirus infection in cats leads to the disease known as feline viral rhinotracheitis (FVR) which is characterized by rhinitis, tracheitis, laryngitis, and conjunctivitis.